Telephone



May 31, 1938.

A. a. ZIMMERMAN 2,119,124

TELEPHONE Filed Der: 30. 1933 2 Sheets-Sheet 1 NVENTOR ART EJIMMERMAN A'h-dRNEY y 1938- A. G. ZIMIMERMAN 2,119,124

TELEPHONE Filed Dec. 30. 1933 2 Sheets-Sheet 2 i mwmm NE IN'VENTOR ARTHUR wwamm BY ATTORNEY Patented May 31, 1938 UNITED STATES.

TELEPHONE Arthur G. Zimmerman, Westmont, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application December so, 1933, Serial No. 704,807

3 Claims.

The present invention relates to whatis known as the batteryless or electromagnetic type of telephone, and more particularly to a variety thereof particularly adapted for portable use or other use under severe conditions of weather and other mechanical abuse.

One object of my invention is to provide such a telephone which is as nearly water-tight as is consistent with adequate acoustic properties.

Another object of my invention is to provide a novel telephone hand-set which is free from acoustic regeneration.

Another object of my invention is to provide a telephone which will not injure the user if he is thrown violently into contact therewith.

Another object of my invention is to provide a water-proof switch in such a telephone.

Another object of my invention is to provide a novel means for connecting the driving-rod to the diaphragm in such a telephone.

Another object of my invention is to provide a novel means for obtaining a permanent and accurate arrangement of the various magnetic airgaps in such a device.

In general, the object of my invention is to provide an acoustically satisfactory telephone hand-set which will continue to function perfectly even under such severe conditions as use on a battleship in action in a storm and with the telephone located immediately adjacent to a short-barreled naval rifle in an open barbette mount.

In the drawings:

Figure 1 is a side view of my improved telephone hand-set.

Figure 2 is a longitudinal section through the mouthpiece thereof.

Figure 3 is a transverse section through an earpiece therefor.

Figure 4 is a view of one of the telephone units from the rear of the diaphragm.

Figure 5 is a vertical section perpendicularly to the middle of Fig. 4.

Figure 6 is a section of the middle of the diaphragm.

Figure 7 is a section of the connection of the driving-rod to the diaphragm, and

Figure 8 is a longitudinal section of the switch.

As shown in Fig. 1, my telephone comprises a handle or body-member I, to which a waterproof cable 2 is secured by a water-proof coupling 3. The member I is made of a rubber compound known commercially as semi-hard rubber, which is flexible and resilient but at the same time has such rigidity as to hold the several parts of the telephone in proper operative relation at all times. The low natural period of vibration of the member I, i. e. of the order of second, prevents any acoustic regeneration through the handle between the receiver 4 and the transmitter 5.

As shown-in Figs. 2 and 3, the transmitter and receiver units each comprise a casing 6 and a face-member 1-, and the member I is provided with correspondingly-shaped recesses into which these parts flt and in which they are resiliently held by the elasticity of the semi-hard rubber.

The transmitter and receiver units are identical in interior construction, as hereinafter described, but each is provided with a proper mouthpiece 8 or ear-piece 9 secured to the cap I by three screws I fitting through the cap 1 into the metal backing-plate II to which the members 8 and 9 are vulcanized. The member 8 is of semi-hard rubber, while the member 9 is of soft sponge rubber, thereby providing the necessary acoustic passages and protecting the user of the device from injury in case of a sudden blow or jar.

Either the transmitter 5, or both the transmitter and the receiver 4, are connected to the cable 2 by a switch, in order that unnecessary noises may not be imposed upon the telephone circuit. My improved switch, indicated at I2, Fig. 1, is shown in more detail in Fig. 8. The switch I2 is provided with a rabbet I3 into which a corresponding tongue on the member I projects to hold the switch rigidly in position when the operating button I4 is pressed. The interior mechanism of the switch may be constructed in any desired or customary fashion. In order to protect the switch from water, and to protect the rest of the mechanism from seepage through the switch, I cement a layer of soft rubber or waterproofed leather l to the member I so as to cover the entire face of the switch I2. It will be apparent that pressure applied on the exterior of the .member I5 will actuate the button I in the same manner as if the latter were unprotected.

Alternately, I may make the cover I5 integral with the member I, inserting the switch through a slot in the rear of the member I, and later cementing this slot shut, or providing a watertight cover therefor.

My device comprises a diaphragm 2I which is actuated in accordance with acoustic frequencies, and which is next described in detail. This diaphragm is composed of aluminum or aluminum alloy, and is corrugated as shown. It is extremely difflcult to solder aluminum, but it is necessary to rigidly attach a driving rod to the center of the diaphragm. I accordingly provide a hole of sufficient size in the center of the diaphragm, and into this I expand and swage down a collar or ferrule 45 of a solderable metal, such as brass. As shown in Fig. 7, the driving-rod 25, also of a solderable metal, may then be inserted through the ferrule 45 and fastened thereto by a small mass 'of solder 46, thus providing a rigid connection between the driving rod and the diaphragm.

In order to provide a proper acoustic bypass from the front to the rear of the diaphragm of my telephone, and in order to then properly connect the several acoustic cavities, I provide holes 41 in the diaphragm. These holes are preferably made so minute, i. e. of the order of .003 or less, that the surface-tension of water in contact therewith will prevent passage of the water therethrough unless under severe hydrostatic pressure. A sufficient number of the holes is provided to secure the proper acoustic response, despite their smallness.

Having now described the general arrangement of my telephone, I will next describe the driving unit thereof, which unit is also described, and in part claimed in the application of Joseph A. Briggs, Serial No. 692,054, filed October 4, 1933 (now Patent No. 2,060,607, dated Nov. 10, 1936), and assigned to the same assignee as the present application. This driving unit or motor mechanism is shown in Figs. 4 and 50f the drawings.

Referring first to Fig. 5, the device is provided with the usual diaphragm 2| which is mounted upon a supporting ring 22, forming the base of the motor unit.

The diaphragm isclamped against the member 22 by means of the retaining ring 23, which is provided with tongues 24, which are clinched over the edge of the member 22 to hold the diaphragm firmly thereagainst. The diaphragm is actuated by longitudinal movement of the driving rod 25, which in turn is actuated by the transverse vibration of the armature 26.

The driving motor of the device is of the polarized type and the laminated silicon steel members 21 constitute the pole pieces thereof. 7

These pole pieces are so shaped as to provide the proper clearance for the armature 26 at its outer end and so as to clamp the armature firmly therebetween at the inner end of the pole pieces. The actuating coil 28 is situated in recesses of the pole pieces, as shown in Fig. 5, and currents passing therethrough cause the armature 26 to be attracted to one or the other pole pieces.

Appropriate magnets are placed in proper relation to the pole pieces 21 with the faces of the magnets in the location shown in dotted lines in Fig. 5, there being one substantially semi-circular cobalt steel magnet on each side of the pole pieces.

A frame member 29 is secured to the base member 22 and projects rearwardly therefrom surrounding the magnets and providing a mounting for the armature and for the pole pieces.

It will be noted that the slot 3| is made so deep that only a comparatively small thickness of metal remains, the reason for which will hereafter appear.

The member 30 is provided with a semi-cylindrical face 33, through which the slot 3| is cut and which fits into the substantially semi-cylindrical recess in the member 29 and is held firmly therein by the cap screws 34. It will be noted that if both cap screws 34 are tightened, the member 30 will be flexed at the base of the recess 3| and will be thereby caused to grip the spacer members 32 to the armature very firmly.

While a tightening of one of the screws 34 and loosening of the other will cause an adjustment of the armature 26 about the center of curvature of the cylindrical surface 33, the ends of the bronze members 32 project into the gap between the lower ends of the pole pieces, as shown in Fig. 5, and are held firmly therebetween by pressure applied longitudinally of the said pole pieces by the bolts 35 and nuts 36 operating against the backplate 31, which abuts against the rear pole pieces and thereby forces both. pole pieces firmly against base member 22.

The faces of the pole pieces 21,which abut against the bronze spacers 32, are curved on a slight radius to permit fiexure of the armature therebetween. It will, therefore, be apparent that if, for example, the screw 34 adjacent to the diaphragm is tightened, the member 30 will be rotated in a clockwise direction and will tend to rotate the armature 26 in the same direction; but due to the firm pivotal hold of the pole pieces 21 upon the members 32, the members 32 and the armature 26 will be flexed between the member 30 and the pole pieces, and the outer end of the armature will, therefore, be flexed in the opposite direction, 1. e., toward the diaphragm.

As shown in Fig. 4, the frame member 29 is provided with a recess at 33 into which the bases of the pole pieces fit, and this recess is wide enough to accommodate also the keys 39, which are riveted to the sides of the said pole pieces, the recess 38 being of a depth substantially identical with the height of the keys 39. Cover plates 40 are provided at each side of the recess 38 and are riveted firmly to the member 29 so as to provide a keyway in which the keys 39 fit quite snugly, this fit being substantially what is known as a press fit.

It will be apparent that when the pole pieces are pressed into place, grasping the members 32 betweenthem, and the nuts 36 are pulled tight and locked by the tongues on the lock brakes 42, it will be substantially impossible for any type of vibration or shock to displace the relative positions of the several members, which will remain the same even though the device as a whole be somewhat deformed.

An appropriate screw 43 is provided for holding the entire motor unit, hereinabove described, in a case of any usual construction, this screw, of course, being inserted through the back of the case and maintaining either the base member 22 or the tongues 24 against an appropriate rim or recess of the case.

I claim:

1. A telephone motor comprising a vibratable armature having a fixed end, pole pieces at each side of said armature, and non-magnetic means on said armature adjacent its fixed end and abutted by said pole pieces for spacing said pole pieces a predetermined distance from each other whereby to provide an air-gap therebetween, said non-magnetic means extending only partially through said air-gap.

2. A telephone motor comprising a vibratable armature having a fixed end, an actuating coil surrounding said armature, pole pieces at each side of said armature and enclosing said coil and non-magnetic means on said armature adjacent its fixed end abutted by said pole pieces for spacing said pole pieces a predetermined distance from each other whereby to provide an air-gap therebetween, said non-magnetic means extending only partially through said air-gap.

3. A telephone motor of the polarized type comprising a pair of laminated pole pieces each provided with a pair of key members, a frame member provided with a slot firmly fitting said key members, and a cover plate constituting the top of the keyway and pressing said key firmly against said frame member.

ARTHUR G. ZIMMERMAN. 

